Semiconductor memory device and manufacturing method thereof

ABSTRACT

A semiconductor memory device, and a method of manufacturing a semiconductor memory device, includes a stacked structure including a plurality of conductive layers for local lines stacked on a semiconductor substrate defined by a cell region and a slimming region to be spaced apart from each other, wherein the plurality of conductive layers for local lines are stacked in a step structure in the slimming region. The semiconductor memory device also includes a plurality of contact plugs formed to penetrate the stack structure in the slimming region, the plurality of contact plugs corresponding to each of the conductive layers for local lines. Each of the plurality of contact plugs includes a protrusion part protruding horizontally, and the protrusion part is connected to a corresponding conductive layer for local lines among the plurality of conductive layers for local lines.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority under 35 U.S.C. § 119(a) toKorean patent application number 10-2019-0121697 filed on Oct. 1, 2019,the entire disclosure of which is incorporated herein by reference.

BACKGROUND 1. Technical Field

The present disclosure generally relates to an electronic device, andmore particularly, to a semiconductor memory device and a manufacturingmethod thereof.

2. Related Art

A semiconductor device, particularly, a semiconductor memory device, isgenerally classified as a volatile memory device or a nonvolatile memorydevice.

A nonvolatile memory device has relatively slow write and read speeds,but retains stored data even when a supply of power is interrupted.Thus, the nonvolatile memory device is used to store data to be retainedregardless of whether power is supplied. Examples of volatile memoryinclude Read Only Memory (ROM), Mask ROM (MROM), Programmable ROM(PROM), Electrically Programmable ROM (EPROM), Electrically Erasable andProgrammable ROM (EEPROM), flash memory, Phase-change RAM (PRAM),Magnetic RAM (MRAM), Resistive RAM (RRAM), Ferroelectric RAM (FRAM), andthe like. The flash memory is classified as NOR type flash memory orNAND type flash memory.

Flash memory has advantages of both RAM, to and from which data isfreely programmed and erased, and ROM, capable of preserving stored dataeven when the supply of power is interrupted. Flash memory has beenwidely used as storage media for portable electronic devices such asdigital cameras, Personal Digital Assistant (PDAs), and MP3 players.

Flash memory devices may be classified as two-dimensional semiconductormemory devices, in which strings are horizontally formed on asemiconductor substrate, or three-dimensional semiconductor memorydevices, in which strings are vertically formed on the semiconductorsubstrate.

A three-dimensional memory device is a memory device devised so as toovercome the limit of degree of integration in two-dimensional memorydevices, and includes a plurality of channel plugs vertically formed ona semiconductor substrate. The channel plugs may include a drain selecttransistor, memory cells, and a source select transistor, which areconnected in series between a bit line and a source line.

SUMMARY

In accordance with an embodiment of the present disclosure, asemiconductor memory device includes a stacked structure including aplurality of conductive layers for local lines stacked on asemiconductor substrate defined by a cell region and a slimming regionto be spaced apart from each other, wherein the plurality of conductivelayers for local lines are stacked in a step structure in the slimmingregion. The semiconductor memory device also includes a plurality ofcontact plugs formed to penetrate the stack structure in the slimmingregion, the plurality of contact plugs corresponding to each of theconductive layers for local lines. Each of the plurality of contactplugs includes a protrusion part protruding horizontally, and theprotrusion part is connected to a corresponding conductive layer forlocal lines among the plurality of conductive layers for local lines.

In accordance with another embodiment of the present disclosure, asemiconductor memory device includes a peripheral circuit structureformed on a semiconductor substrate and a memory cell array formed abovethe peripheral circuit structure. The semiconductor memory device alsoincludes a plurality of contact plugs penetrating a slimming region ofthe memory cell array, the plurality of contact plugs being connected toa plurality of metal lines of the peripheral circuit structure. Thememory cell array includes a plurality of conductive layers for locallines, which are stacked in a step structure in the slimming region.Further, each of the plurality of contact plugs includes a protrusionpart protruding horizontally, and the protrusion part is connected to acorresponding conductive layer for local lines among the plurality ofconductive layers for local lines.

In accordance with still another embodiment of the present disclosure, amethod of manufacturing a semiconductor memory device includes: forminga stack structure including a plurality of first material layers and aplurality of second material layers, which are alternately stacked in acell region and a slimming region, wherein the first material layers andthe second material layers are stacked in a step structure in which thesecond material layers are exposed in the slimming region; forming asacrificial layer along an upper surface of the stack structure in theslimming region; and allowing the sacrificial layer to remain on onlythe upper surface of the stack structure by removing the sacrificiallayer formed on a sidewall of the stack structure having the stepstructure. The method also includes: forming an interlayer insulatinglayer on the top of the entire structure, and forming a plurality ofcontact holes penetrating the interlayer insulating layer, thesacrificial layer, and the stack structure; forming an insulating layerfor spacers on sidewalls of the second material layers exposed throughsidewalls of the contact holes; removing the second material layers, andforming conductive layers for local word lines in spaces in which thesecond material layers are removed; removing the sacrificial layerexposed through the sidewalls of the contact holes; and forming contactplugs each having a protrusion part by filling, with a conductivematerial, the contact holes each including a space in which thesacrificial layer is removed.

BRIEF DESCRIPTION OF THE DRAWINGS

Example embodiments will now be described hereinafter with reference tothe accompanying drawings; however, they may be embodied in differentforms and should not be construed as being limited to the embodimentsset forth herein. Rather, these embodiments are provided so that thisdisclosure will be enabling, and will convey the scope of the exampleembodiments to those skilled in the art.

In the drawings, dimensions may be exaggerated for clarity ofillustration. It will be understood that when an element is referred toas being “between” two elements, it can be the only element between thetwo elements, or one or more intervening elements may also be present.Like reference numerals refer to like elements throughout.

FIG. 1 is a diagram illustrating a semiconductor memory device inaccordance with an embodiment of the present disclosure.

FIG. 2 is a view illustrating an arrangement between a memory cell arrayand peripheral circuits.

FIG. 3 is a view illustrating a memory cell array including memoryblocks formed in a three-dimensional structure.

FIG. 4 is a view illustrating a configuration of a memory block and aconnection relationship between the memory block and the peripheralcircuits.

FIG. 5 is a sectional view of a semiconductor memory device,illustrating a cell region and a slimming region.

FIGS. 6 to 15 are views illustrating a manufacturing method of asemiconductor memory device in accordance with an embodiment of thepresent disclosure.

FIG. 16 is a three-dimensional view illustrating a contact plug shown inFIG. 15.

FIG. 17 is a diagram illustrating an embodiment of a memory systemincluding the semiconductor memory device shown in FIG. 1.

FIG. 18 is a diagram illustrating another embodiment of the memorysystem including the semiconductor memory device shown in FIG. 1.

DETAILED DESCRIPTION

The specific structural or functional description disclosed herein ismerely illustrative for the purpose of describing embodiments accordingto the concept of the present disclosure. The embodiments according tothe concept of the present disclosure can be implemented in variousforms, and should not be construed as limited to the embodiments setforth herein.

Hereinafter, embodiments of the present disclosure will be described indetail with reference to the accompanying drawings in order for thoseskilled in the art to be able to readily implement the technical spiritof the present disclosure.

Some embodiments provide a semiconductor memory device capable ofimproving a process of connecting local lines of memory blocks includedin the semiconductor memory device to peripheral circuits, and amanufacturing method of the semiconductor memory device.

FIG. 1 is a diagram illustrating a semiconductor memory device 1100 inaccordance with an embodiment of the present disclosure.

Referring to FIG. 1, the semiconductor memory device 1100 may include amemory cell array 100 capable of storing data and peripheral circuits110 capable of performing a program, read, or erase operation of thememory cell array 100.

The memory cell array 100 may include a plurality of memory blocksincluding nonvolatile memory cells. Local lines LL may be connected toeach of the memory blocks, and bit lines BL may be commonly connected tothe memory blocks.

The peripheral circuits 110 may include control logic 111, a voltagegenerator 112, a row decoder 113, a page buffer group 114, a columndecoder 115, and an input/output circuit 116.

The control logic 111 may control the voltage generator 112, the rowdecoder 113, the page buffer group 114, the column decoder 115, and theinput/output circuit 116 according to a command CMD and an address ADD.For example, the control logic 111 may output an operation signal OPSand a page buffer control signal PBSIG in response to the command CMD,and output a row address RADD and a column address CADD in response tothe address ADD. The control logic 111 may be implemented as hardware,software, or a combination of hardware and software. For example, thecontrol logic 111 may be a control logic circuit operating in accordancewith an algorithm and/or a processor executing control logic code.

The voltage generator 112 may generate and output operating voltages Vopnecessary for a program, read, or erase operation in response to theoperation signal OPS. For example, the voltage generator 112 maygenerate and output operating voltages Vop such as a program voltage, aread voltage, an erase voltage, and a pass voltage.

The row decoder 113 may transfer the operating voltages Vop to aselected memory block through the local lines LL in response to the rowaddress RADD.

The page buffer group 114 may include a plurality of page buffersconnected to the selected memory block through the bit lines BL. Thepage buffer group 114 may temporarily store data in a program or readoperation in response to the page buffer control signal PBSIG.

The column decoder 115 may transmit data between the page buffer group114 and the input/output circuit 116 in response to the column addressCADD.

The input/output circuit 116 may receive a command CMD and an addressADD from an external device and transmit the command CMD and the addressADD to the control logic 111. The input/output circuit 116 may transmitdata DATA received from the external device to the column address 115 ina program operation, and output data DATA received from the columnaddress 115 to the external device in a read operation.

FIG. 2 is a view illustrating an arrangement between the memory cellarray 100 and the peripheral circuits 110.

Referring to FIG. 2, the memory cell array 100 and the peripheralcircuits 110, which are described in FIG. 1, may be variously arranged.For example, when a substrate is disposed in an X-Y direction, thememory cell array 100 and the peripheral circuits 110 may also bedisposed in parallel to each other in the X-Y direction (210).Alternatively, the memory cell array 100 may be disposed above theperipheral circuits 110 in a direction (Z direction) vertical to thesubstrate (220). That is, the peripheral circuits 110 may be disposedbetween the substrate and the memory cell array 100.

FIG. 3 is a view illustrating the memory cell array 100 including memoryblocks BLK1 to BLKn formed in a three-dimensional structure.

Referring to FIG. 3, when the memory cell array 100 includes memoryblocks BLK1 to BLKn formed in a three-dimensional structure, the memoryblocks BLK1 to BLKn may be arranged in a Y direction. The Y directionmay be a direction in which the bit lines BL shown in FIG. 1 extend.

Although a case where the memory cell array 100 includes one plane isillustrated in FIG. 3, the memory cell array 100 may include a pluralityof planes. The plurality of planes may be arranged in an X direction,and memory blocks included in each plane may be arranged in the Ydirection in the corresponding plane.

FIG. 4 is a view illustrating a configuration of a memory block BLKn anda connection relationship between the memory block BLKn and theperipheral circuits 110.

The plurality of memory blocks BLK1 to BLKn described in FIG. 3 may beconfigured identically to one another. For example, in FIG. 4, thememory block BLKn may represent any memory block among the plurality ofmemory blocks BLK1 to BLKn.

Referring to FIG. 4, the memory block BLKn formed in thethree-dimensional structure may include a cell region CR in which memorycells are included and a slimming region SR for electrically connectingthe peripheral circuits 110 and the cell region CR to each other. Forexample, a plurality of vertical strings in which memory cells andselect transistors are stacked may be included in the cell region CR,and ends of a plurality of gate lines, which are connected to the memorycells and the select transistors, may be included in the slimming regionSR. For example, in the slimming region SR, the gate lines may bestacked in a step structure in which a gate line located at a relativelylower portion extends longer than that located at a relatively upperportion. The gate lines exposed by the step structure may be connectedto the peripheral circuits 110 through contact plugs.

When the peripheral circuits 110 and the memory block BLKn are disposedin parallel to each other (in the X direction) (210), a plurality oflines ML for electrically connecting the slimming region SR and theperipheral circuits 110 to each other may be formed. For example, in thestructure 210, the plurality of lines ML may be disposed to extend alongthe X direction and to be spaced apart from each other along the Ydirection.

When the peripheral circuits 110 are disposed under the memory blockBLKn (in the Y direction) (220A), a plurality of lines ML forelectrically connecting the slimming region SR and the peripheralcircuits 110 to each other may be disposed to extend along the Zdirection and to be spaced part from each other along the Y direction.As shown in the drawing, the plurality of lines ML extend above theslimming region SR (in the Z direction), extend horizontally (in the Xdirection) up to a region out of the slimming region SR, and then extendvertically in the lower direction (Z direction), to be connected theperipheral circuits 110 disposed under the memory block BLKn.

In another embodiment, when the peripheral circuits 110 are disposedunder the memory block BLKn (in the Y direction) (220B), a plurality oflines ML for electrically connecting the slimming region SR and theperipheral circuits 110 to each other penetrate the slimming region SRand are connected to the peripheral circuits 110 disposed under thememory block BLKn.

In an embodiment of the present disclosure, a semiconductor memorydevice in which the plurality of lines ML penetrate the slimming regionSR and are connected to the peripheral circuit 110 disposed under thememory block BLKn as shown in the structure 220B will be described.

FIG. 5 is a sectional view of a semiconductor memory device,illustrating a cell region and a slimming region.

In FIG. 5, a case where peripheral circuits 110 are disposed under amemory cell array 100 including a plurality of memory cells, and aplurality of lines penetrate a slimming region SR of the memory cellarray 100 and are connected to the peripheral circuits 110 as shown inthe structure 220B described in FIG. 4 is illustrated as an embodiment.

Referring to FIG. 5, a cell region CR and the slimming region SR aredisposed adjacent to each other in one direction X-X′.

The semiconductor memory device in accordance with an embodiment of thepresent disclosure may have a Peri Under Cell (PUC) structure. Theperipheral circuits 110 may be provided under the memory cell array 100.

In an embodiment, the peripheral circuits 110 may include a row decoder113. Although not shown in the drawing, the peripheral circuits 110 mayfurther include at least one of the control logic 111, the voltagegenerator 112, the page buffer group 114, the column decoder 115, andthe input/output circuit 116, which are shown in FIG. 1.

A semiconductor substrate 400 may be a single crystalline siliconsubstrate. The semiconductor substrate 400 may include a polysiliconsubstrate, a Silicon On Insulator (SOI) substrate, or a Germanium OnInsulator (GeOI) substrate. The semiconductor substrate 400 may includeSi, Ge, SiGe, etc.

A first interlayer insulating layer 301 covering the peripheral circuits110 including the row decoder 113 may be provided on the semiconductorsubstrate 400. The first interlayer insulating layer 301 may include,for example, an insulating layer such as a silicon oxide layer. Metallines 401 and 303 connected to the row decoder 113 may be provided inthe first interlayer insulating layer 301.

An upper substrate 305 is stacked on the first interlayer insulatinglayer 301, and second interlayer insulating layers 307 and conductivelayers 331 for local lines are alternately stacked on the uppersubstrate 305. The second interlayer insulating layer 307 is stacked onthe uppermost conductive layer 331 for local lines.

The upper substrate 305 may include polycrystalline silicon. The uppersubstrate 305 may be generated using a method of forming a predeterminedpolycrystalline silicon region on the first interlayer insulating layer301 and growing polycrystalline silicon by using the polycrystallinesilicon region as a seed layer. The upper substrate 305 may be formed tobe separated in a region in which a contact plug 333 connected to therow decoder 113 is formed in the slimming region SR.

The second interlayer insulating layer 307 may include an insulatingmaterial such as oxide, and the conductive layers 331 for local linesmay include a conductive material such as polysilicon or tungsten.

A conductive layer stacked at the lowermost portion among the conductivelayers 331 for local lines may be a source select line, a conductivelayer stacked at the uppermost portion among the conductive layers 331for local lines may be a drain select line, and the other conductivelayers for local lines may be word lines.

A channel plug CP is disposed in the cell region CR of the memory cellarray 100. The channel plug CP penetrates the second interlayerinsulating layers 307 and the conductive layers 331 for local lines, andis formed vertically to the upper substrate 305. The channel plug CPincludes a gap fill layer 315, a channel pattern 313 surrounding the gapfill layer 315, and a memory pattern 311 surrounding the channel pattern313. For example, the memory pattern 311 may include at least one of acharge blocking layer, a data storage layer, and a tunnel insulatinglayer, and the data storage layer may include a floating gate such assilicon, a charge trap material such as nitride, a phase changematerial, nano dots, and the like. In addition, the channel pattern 313may be formed in a shape completely filled in a central region, or beformed in a structure having an open central region. The gap fill layer315 may be formed in the open central region.

The conductive layers 331 for local lines are disposed to extend fromthe cell region CR to the slimming region SR. The conductive layers 331for local lines are stacked in the shape of steps in the slimming regionSR. For example, the conductive layers 331 for local lines may be formedin a step structure in which a conductive layer 331 for local lines,which is disposed at a relatively lower portion, extends longer thanthat disposed at a relatively upper portion.

Each of the conductive layers 331 for local lines is electricallyconnected to any one of a plurality of contact plugs 333 whichvertically penetrate the conductive layer 331 for local lines and thesecond interlayer insulating layers 307 and are connected to the lowermetal line 303. Each of the plurality of contact plugs 333 has aprotrusion part protruding in a horizontal direction, and a lowersurface of the protrusion part is in contact with an upper surface of anend portion of any one of the conductive layers 331 for local lines. Forexample, each of the contact plugs 333 penetrates an end portion of acorresponding conductive layer 331 for local lines and extends in avertical direction, and includes a protrusion part in electrical andphysical contact with an upper surface of the end portion of thecorresponding conductive layer 331 for local lines. Also, each of thecontact plugs 333 may penetrate conductive layers 331 for local lines,which are disposed under a corresponding conductive layer 331 for locallines. A insulating layer 327 for spacers is formed in regions in whichthe contact plugs 333 and the conductive layers 331 for local linesintersect each other, i.e., on sidewalls of the contact plugs 333penetrating the conductive layers 331 for local lines. The insulatinglayer 327 for spacers prevents each of the contact plugs 333 from beingelectrically connected to the other conductive layers 331 for locallines except a corresponding conductive layer 331 for local lines. Theinsulating layer 327 for spacers may be configured in a shapesurrounding the sidewalls of the contact plugs 333 in the regions inwhich the contact plugs 333 and the conductive layers 331 for locallines intersect each other. Each of the contact plugs 333 is connectedto a conductive layer 331 for local lines, which is disposed at theuppermost portion, among the conductive layers 331 for local lines,which are penetrated thereby, through the protrusion part.

Additionally, a pad layer 321 may be formed on the top of the protrusionparts of the contact plugs 333, and a third interlayer insulating layer323 may be formed in a space between an upper portion of the cell regionCR and the contact plugs 333 of the slimming region SR.

FIGS. 6 to 15 are views illustrating a manufacturing method of asemiconductor memory device in accordance with an embodiment of thepresent disclosure.

The manufacturing method of the semiconductor memory device inaccordance with an embodiment of the present disclosure will bedescribed as follows with reference to FIGS. 6 to 15.

In an embodiment of the present disclosure, processes after peripheralcircuits 110 including a row decoder 113 are formed on a semiconductorsubstrate, and a lower metal line 303 connected to the row decoder 113is formed in a first interlayer insulating layer 301 will be described.

Referring to FIG. 6, an upper substrate 305 is formed on the firstinterlayer insulating layer 301 including a lower metal line 303. Theupper substrate 305 may include a source line layer, and the source linelayer may be a doped semiconductor layer. For example, the source linelayer may be a semiconductor layer doped with an n-type impurity. In anembodiment, the source line layer may be formed by injecting an impurityinto a surface of the upper substrate 305, or be formed by depositing atleast one doped silicon layer on the upper substrate 305. In anembodiment, the source line layer may be formed by forming the firstinterlayer insulating layer 301 on the peripheral circuits 110 shown inFIG. 5 and then depositing at least one doped silicon layer on the firstinterlayer insulating layer 301.

In addition, the upper substrate 305 may be formed in a shape in which aregion in which the lower metal line 303 is formed in the slimmingregion SR is open.

Subsequently, a stack structure ST in which first material layers 307and second material layers 309 are alternately stacked is formed on acell region CR and the slimming region SR. The second material layers309 may be sacrificial layers for forming conductive layers such as aword line, a select line, and a pad, and the first material layers 307may be second interlayer insulating layers for insulating the stackedconductive layers from each other.

The first material layers 307 are formed of a material having an etchingrate higher than that of the second material layers 309. In an example,the first material layers 307 may include an insulating material such asoxide, and the second material layers 309 may include a sacrificialmaterial such as nitride.

Referring to FIG. 7, a channel hole in which a channel plug CP is to beformed in the cell region is formed by etching the stack structure STformed on the cell region CR. Subsequently, the channel plug CPincluding a channel pattern 313 and a memory pattern 311 surrounding thechannel pattern 313 is formed in the channel hole. For example, thememory pattern 311 is formed on a sidewall of the channel hole. Thememory pattern 311 may include at least one of a charge blocking layer,a data storage layer, and a tunnel insulating layer, and the datastorage layer may include a floating gate such as silicon, a charge trapmaterial such as nitride, a phase change material, nano dots, and thelike. Subsequently, the channel plug CP is formed by completely fillinga central region of the channel hole with the channel pattern 313. Inanother embodiment, the channel pattern 313 may be formed in a structurein which the central region of the channel hole is open, and a gap filllayer 315 may be formed in the open central region.

Subsequently, an etching process is performed such that the stackstructure ST formed on the slimming region SR has a step shape. Forexample, in the slimming region SR, the first material layers and thesecond material layers of the stack structure ST may be formed in theshape of steps extending longer as becoming closer to the bottomthereof. For example, the stack structure ST may be formed in a stepstructure in which the second material layers exposed upward in theslimming region SR.

Referring to FIG. 8, sacrificial layers 317 and 319 and a pad layer 321are formed on the entire structure including the cell region CR and theslimming region SR.

The sacrificial layers 317 and 319 may be formed to include a firstsacrificial layer 317 and a second sacrificial layer 319. The firstsacrificial layer 317 may be formed on the top of the exposed secondmaterial layers. In an example, the first sacrificial layer 317 may beformed of an oxide layer formed using an oxidation process. The secondsacrificial layer 319 may be formed along an upper surface of the entirestructure including the first sacrificial layer 317. In an example, thesecond sacrificial layer 310 may be formed of an undoped polysiliconlayer.

The pad layer 321 may be formed along an upper surface of the entirestructure including the sacrificial layers 317 and 319. In an example,the pad layer 321 may be formed of an oxide layer. In an example, athickness of the pad layer 321 formed on the top of the stack structureST may be thicker than that of the pad layer 321 formed on a sidewall ofthe stack structure ST.

Referring to FIG. 9, the sacrificial layers 317 and 319 and the padlayer 321, which are formed on the sidewall of the stack structure ST,are removed by performing an etching process. For example, the etchingprocess of the pad layer 321 may be performed using a wet etchingprocess. Because the pad layer 321 formed on the sidewall of the stackstructure ST is thinner than the pad layer 321 formed on the top of thestack structure ST in the wet etching process, the pad layer 321 formedon the sidewall of the stack structure ST may be removed in a state inwhich the pad layer 321 remains on the top of the stack structure ST.Subsequently, the sacrificial layers 317 and 319 exposed as the padlayer 321 is removed are removed by performing a dry etching process.That is, the sacrificial layers 317 and 319 formed on the sidewall ofthe stack structure ST are removed. Therefore, the sacrificial layers317 and 319 and the pad layer 321 remain on only the top of the secondmaterial layers in the slimming region SR.

Referring to FIG. 10, a third interlayer insulating layer 323 is formedon the top of the entire structure including the cell region CR and theslimming region SR. The third interlayer insulating layer 323 may beformed of an oxide layer. Subsequently, a hard mask pattern 325 isformed on the top of the third interlayer insulating layer 323. The hardmask pattern 325 may be formed such that a region in which a contacthole is formed is open.

Subsequently, contact holes CH which penetrate the third interlayerinsulating layer 323, the pad layer 321, the sacrificial layers 319 and317, the stack structure ST, and the first interlayer insulating layer301 and allows the lower metal line 303 to be exposed therethrough areformed by performing an etching process using the hard mask pattern 325.

Referring to FIG. 11, the hard mask pattern 325 is removed, and thesecond material layers exposed through sidewalls of the contact holesare etched to a partial thickness, thereby forming a concave portion Aat the sidewall of each of the contact holes. The partial thickness towhich the second materials are etched may be thinner than a horizontalwidth of the sacrificial layers 317 and 319. For example, portions ofend portions of the second material layers overlap with the sacrificiallayers 317 and 319. For example, the partial thickness to which thesecond material layers are etched may be 50 nm to 100 nm.

Referring to FIG. 12, an insulating layer 327 for spacers is formed onthe sidewall of the contact hole. The insulating layer 327 for spacersmay be formed to be embedded in the concave portion formed on thesidewall of the contact hole. Subsequently, the contact hole may begap-filled with a polysilicon layer 329 for support forming.

Referring to FIG. 13, at least one slit (not shown) penetrating thethird interlayer insulating layer 323 and the stack structure ST isformed in the cell region CR and the slimming region SR, and a sidewallof the stack structure ST is exposed through the slit. Subsequently, thesecond material layers exposed through the slit are removed, andconductive layers 331 for local lines are formed in regions in which thesecond material layers are removed. The conductive layers 331 for locallines may be used as the local lines LL shown in FIG. 1.

Referring to FIG. 14, sidewalls of the sacrificial layers (317 and 319shown in FIG. 13) are exposed by removing the polysilicon layer forsupport forming, which is formed in the contact hole, and etching, to apartial thickness, the insulating layer 327 for spacers, which is formedon the sidewall of the contact hole. The insulating layer 327 forspacers remains in the concave portion at the sidewall of the contacthole, to prevent the conductive layers 331 for local lines from beingexposed through the contact hole.

Subsequently, the exposed sacrificial layers are removed by performingan etching process. An upper surface of an end of each of the conductivelayers 331 for local lines is exposed through a space B in which thesacrificial layers are removed.

Referring to FIG. 15, contact plugs 333 are formed by filling thecontact holes with a conductive material. Each of the contact plugs 333is electrically connected to a corresponding lower metal line 303 on thebottom thereof. Each of the contact plugs 333 is formed to have aprotrusion part C in a region in which the sacrificial layers areremoved. A lower surface of the protrusion part C is electricallyconnected to a corresponding conductive layer 331 for local lines.

FIG. 16 is a three-dimensional view illustrating the contact plug shownin FIG. 15.

The contact plug 333 is formed in a cylindrical shape extending in avertical direction of a substrate, so that a lower surface of thecontact plug 333 is electrically connected to the lower metal line 303while being in contact with the lower metal line 303. Also, a portion ofthe sidewall of the contact plug 333 may include the protrusion part Cprotruding in a horizontal direction of the substrate, and theprotrusion part C may be provided in a disk shape. A portion of thelower surface of the protrusion part C is electrically connected to acorresponding conductive layer (331 shown in FIG. 15) for local lineswhile being in contact with the corresponding conductive layer for locallines.

FIG. 17 is a diagram illustrating an embodiment of a memory system 1000including the semiconductor memory device 1100 shown in FIG. 1.

Referring to FIG. 17, the memory system 1000 may include a plurality ofsemiconductor memory devices 1100 configured to store data and acontroller 1200 configured to communicate between the semiconductormemory devices 1100 and a host 2000.

Each of the semiconductor memory devices 1100 may be the semiconductormemory device described in the above-described embodiment.

The semiconductor memory devices 1100 may be connected to the controller1200 through a plurality of system channels sCH. For example, aplurality of semiconductor memory devices 1100 may be connected to onesystem channel sCH, and the plurality of system channels sCH may beconnected to the controller 1200.

The controller 1200 may communicate between the host 2000 and thesemiconductor memory devices 1100. The controller 1200 may control thesemiconductor memory devices 1100 in response to a request from the host2000, or perform a background operation for improving performance of thememory system 1000 even when there is no request from the host 2000.

The host 2000 may generate requests for various operations, and outputthe generated requests to the memory system 1000. For example, therequests may include a program request capable of controlling a programoperation, a read request capable of controlling a read operation, anerase request capable of controlling an erase operation, and the like.The host 2000 may communicate with the memory system 1000 throughvarious interfaces such as Peripheral Component Interconnect-Express(PCI-E), Advanced Technology Attachment (ATA), Serial ATA (SATA),Parallel ATA (PATA), Serial Attached SCSI (SAS), or Non-Volatile MemoryExpress (NVMe), a Universal Serial Bus (USB), a Multi-Media Card (MMC),an Enhanced Small Disk Interface (ESDI), and Integrated DriveElectronics (IDE).

FIG. 18 is a diagram illustrating another embodiment of a memory systemincluding the semiconductor memory device 1100 shown in FIG. 1.

Referring to FIG. 18, the memory system may be implemented with a memorycard 3000. The memory card 3000 may include a semiconductor memorydevice 1100, a controller 1200, and a card interface 7100.

The controller 1200 may control data exchange between the semiconductormemory device 1100 and the card interface 7100. In some embodiments, thecard interface 7100 may be a Secure Digital (SD) card interface or aMulti-Media Card (MMC) interface, but the present disclosure is notlimited thereto.

The card interface 7100 may interface data exchange between a host 2000and the controller 1200 according to a protocol of the host 2000. Insome embodiments, the card interface 7100 may support a Universal SerialBus (USB) protocol and an Inter-Chip (IC)-USB protocol. The cardinterface 7100 may mean hardware capable of supporting a protocol usedby the host 2000, software embedded in the hardware, or a signaltransmission scheme.

When the memory card 3000 is connected to a host interface of the host2000 such as a PC, a tablet PC, a digital camera, a digital audioplayer, a cellular phone, console video game hardware, or a digitalset-top box, the host interface may perform data communication with thesemiconductor memory device 1100 through the card interface 7100 and thecontroller 1200 under the control of a microprocessor of the host 2000.

In accordance with the present disclosure, a forming process of contactplugs connecting local lines of the semiconductor memory device toperipheral circuits can be improved.

While the present disclosure has been shown and described with referenceto certain embodiments thereof, it will be understood by those skilledin the art that various changes in form and details may be made thereinwithout departing from the spirit and scope of the present disclosure asdefined by the appended claims and their equivalents. Therefore, thescope of the present disclosure should not be limited to theabove-described embodiments but should be determined by not only theappended claims but also the equivalents thereof.

In the above-described embodiments, all steps may be selectivelyperformed or part of the steps and may be omitted. In each embodiment,the steps are not necessarily performed in accordance with the describedorder and may be rearranged. The embodiments disclosed in thisspecification and drawings are only examples to facilitate anunderstanding of the present disclosure, and the present disclosure isnot limited thereto. That is, it should be apparent to those skilled inthe art that various modifications can be made on the basis of thetechnological scope of the present disclosure.

Meanwhile, the embodiments of the present disclosure have been describedin the drawings and specification. Although specific terminologies areused here, those are only to explain the embodiments of the presentdisclosure. Therefore, the present disclosure is not restricted to theabove-described embodiments and many variations are possible within thespirit and scope of the present disclosure. It should be apparent tothose skilled in the art that various modifications can be made on thebasis of the technological scope of the present disclosure in additionto the embodiments disclosed herein.

What is claimed is:
 1. A semiconductor memory device comprising: astacked structure including a plurality of conductive layers for locallines stacked on a semiconductor substrate defined by a cell region anda slimming region to be spaced apart from each other, wherein theplurality of conductive layers for local lines are stacked in a stepstructure in the slimming region; and a plurality of contact plugsformed to penetrate the stack structure in the slimming region, theplurality of contact plugs corresponding to each of the conductivelayers for local lines, wherein each of the plurality of contact plugsincludes a protrusion part protruding horizontally, and the protrusionpart is connected to a corresponding conductive layer for local linesamong the plurality of conductive layers for local lines.
 2. Thesemiconductor memory device of claim 1, wherein the protrusion part ofeach of the plurality of contact plugs extends and protrudes to an endportion of the corresponding conductive layer for local lines.
 3. Thesemiconductor memory device of claim 2, wherein the protrusion part ofeach of the plurality of contact plugs is connected to an upper surfaceof the end portion of the corresponding conductive layer for locallines.
 4. The semiconductor memory device of claim 2, wherein a lowersurface of the protrusion part of each of the plurality of contact plugsis connected to an upper surface of the end portion of the correspondingconductive layer for local lines.
 5. The semiconductor memory device ofclaim 2, wherein each of the plurality of contact plugs corresponds to aconductive layer for local lines, which is disposed at the uppermostportion, among the plurality of conductive layers for local linespenetrated by the contact plug, wherein the protrusion part of each ofthe plurality of contact plugs is connected to the conductive layer forlocal lines, which is disposed at the uppermost portion.
 6. Thesemiconductor memory device of claim 1, further comprising insulatinglayers for spacers, which are formed on sidewalls of the contact plugsin regions in which the plurality of contact plugs and the plurality ofconductive layers for local lines intersect each other.
 7. Thesemiconductor memory device of claim 6, wherein the insulating layersfor spacers separate the sidewalls of the plurality of contact plugsfrom the plurality of conductive layers for local lines.
 8. Thesemiconductor memory device of claim 1, further comprising a peripheralcircuit structure disposed under the stack structure, wherein theplurality of contact plugs are connected to a plurality of metal linesconnected to the peripheral circuit structure.
 9. The semiconductormemory device of claim 8, wherein the peripheral circuit structurecomprises a row decoder.
 10. A semiconductor memory device comprising: aperipheral circuit structure formed on a semiconductor substrate; amemory cell array formed above the peripheral circuit structure; and aplurality of contact plugs penetrating a slimming region of the memorycell array, the plurality of contact plugs being connected to aplurality of metal lines of the peripheral circuit structure, wherein,the memory cell array includes a plurality of conductive layers forlocal lines, which are stacked in a step structure in the slimmingregion, wherein each of the plurality of contact plugs includes aprotrusion part protruding horizontally, and the protrusion part isconnected to a corresponding conductive layer for local lines among theplurality of conductive layers for local lines.
 11. The semiconductormemory device of claim 10, wherein the protrusion part of each of theplurality of contact plugs extends and protrudes to an end portion ofthe corresponding conductive layer for local lines.
 12. Thesemiconductor memory device of claim 11, wherein a lower surface of theprotrusion part of each of the plurality of contact plugs is connectedto an upper surface of the end portion of the corresponding conductivelayer for local lines.
 13. The semiconductor memory device of claim 10,further including insulating layers for spacers, which are formed onsidewalls of the contact plugs in regions in which the plurality ofcontact plugs and the plurality of conductive layers for local linesintersect each other.
 14. The semiconductor memory device of claim 10,wherein the peripheral circuit structure comprises a row decoder,wherein the row decoder is connected to the plurality of conductivelayers for local lines through the plurality of metal lines and theplurality of contact plugs.
 15. A method of manufacturing asemiconductor memory device, the method comprising: forming a stackstructure including a plurality of first material layers and a pluralityof second material layers, which are alternately stacked in a cellregion and a slimming region, wherein the first material layers and thesecond material layers are stacked in a step structure in which thesecond material layers are exposed in the slimming region; forming asacrificial layer along an upper surface of the stack structure in theslimming region; allowing the sacrificial layer to remain on only theupper surface of the stack structure by removing the sacrificial layerformed on a sidewall of the stack structure having the step structure;forming an interlayer insulating layer on the top of the entirestructure, and forming a plurality of contact holes penetrating theinterlayer insulating layer, the sacrificial layer, and the stackstructure; forming an insulating layer for spacers on sidewalls of thesecond material layers exposed through sidewalls of the contact holes;removing the second material layers, and forming conductive layers forlocal word lines in spaces in which the second material layers areremoved; removing the sacrificial layer exposed through the sidewalls ofthe contact holes; and forming contact plugs each having a protrusionpart by filling, with a conductive material, the contact holes eachincluding a space in which the sacrificial layer is removed.
 16. Themethod of claim 15, wherein forming the sacrificial layer comprises:forming a first sacrificial layer including an oxide layer on an uppersurface of the second material layer; forming a second sacrificial layerincluding an undoped polysilicon layer along a surface of the top of theentire structure including the first sacrificial layer; and forming apad layer along an upper surface of the sacrificial layer, after thesacrificial layer is formed.
 17. The method of claim 15, wherein formingthe insulating layer for spacers comprises: forming a concave portion ata sidewall of the contact hole by etching the sidewalls of the secondmaterial layers exposed through the sidewalls of the contact holes to acertain thickness; forming an insulating layer for spacers on thesidewalls of the contact holes each including the concave portion; andallowing the insulating layer for spacers to remain in only the concaveportion by performing an etching process.
 18. The method of claim 15,wherein, in the removing of the sacrificial layer exposed through thesidewalls of the contact holes, spaces in which the sacrificial layer isremoved expose upper surfaces of ends of the conductive layers for localword lines.
 19. The method of claim 18, wherein the contact plugs arerespectively connected to the upper surfaces of the ends of theconductive layers for local word lines.
 20. The method of claim 15,wherein the contact plugs are connected to a peripheral circuitstructure disposed at a lower portion of the cell region and theslimming region.